In OFDM (Orthogonal Frequency-Division Multiplexing) communication, an input signal is applied a subcarrier modulation, and is subjected to IFFT (Inverse Fast Fourier Transformation) to generate a baseband signal. As a result of this, the number of subcarriers is increased and baseband signals having high peaks are generated, thereby causing high PAPR (Peak-to-Average Power Ratio). A high PAPR requires amplifiers that exhibit linearity across a wide region in order to achieve distortion-free transmissions of signals. In this regard, techniques for PAPR reduction have been proposed.
In order to reduce PAPR, an orthogonal frequency-division multiplexing communication device according to Unexamined Japanese Patent Application Kokai Publication No. 2006-165781, performs, prior to executing IFFT, a subcarrier modulated signal phase control based on a calculated optimal phase, that is calculated using a sequential decision procedure.
In OFDM communication, a reduction of PAPR is the issue that has been addressed. The orthogonal frequency-division multiplexing communication device according to Unexamined Japanese Patent Application Kokai Publication No. 2006-165781, requires iterative calculations to obtain an optimal phase for minimizing PAPR and requires individual phase control per each subcarrier.